How to fix Error 649 on Windows 11

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Troubleshooting Guide: Error 649 – Mount Point Resolution Failure

Why This Error Happens

Error 649 occurs when the Windows I/O subsystem attempts a create operation on a path containing a mount point, but that mount point resolves to a volume that is not attached to the device object making the request. This typically happens due to a corrupted or stale mount point in the volume mount point database (stored in the NTFS reparse point metadata), a volume that was detached or reassigned without properly cleaning up existing mount point references, or a driver/filter (such as a virtualization, backup, or storage tiering driver) presenting a device object that doesn’t match the volume’s actual attachment chain. It’s commonly seen with dynamic disks, Storage Spaces, VHD/VHDX mounts, or third-party disk management tools that manipulate volume GUIDs.

Step-by-Step Resolution Guide

  1. Identify the offending mount point
    Open an elevated Command Prompt and run:
   mountvol

This lists all volumes and their mount points. Cross-reference the path from the error against the listed volume GUIDs to find the mismatched mount point.

  1. Remove the broken mount point
    Navigate to the parent folder hosting the mount point (e.g., C:\MountedVolumes\Data) and unmount it:
   mountvol C:\MountedVolumes\Data /D

If the folder is inaccessible, delete the reparse point using fsutil:

   fsutil reparsepoint delete C:\MountedVolumes\Data

  1. Verify volume attachment via Disk Management
    Open diskmgmt.msc, confirm the target volume is Online and Healthy, and check whether it still has an assigned drive letter or mount path. If it shows as “Foreign,” “Offline,” or “No Media,” right-click and bring it Online or import it (for dynamic/Storage Spaces disks).

  2. Re-create the mount point correctly
    Once the volume is confirmed online and attached, re-add the mount point pointing to the correct volume GUID:

   mountvol C:\MountedVolumes\Data \\?\Volume{correct-guid}\

Ensure the GUID matches the current mountvol output exactly — copy-paste rather than retyping.

  1. Check for conflicting filter drivers
    If the issue persists, run fltmc filters to check for third-party storage filter drivers (backup agents, antivirus, virtualization tools). Temporarily disable or update any recently installed storage/backup software, then retry the operation.

Alternative or Verification Steps

  • Verify the fix: Re-run the original operation (e.g., file creation, backup job, or application launch) that triggered Error 649, and confirm via Event Viewer (eventvwr.msc → Windows Logs → System) that no new Error 649 entries appear.
  • Alternative fix: If the mount point database appears persistently corrupted, run chkdsk /f on the affected volume, then reboot and recreate the mount points from scratch using Disk Management instead of the command line.